Ring closing metathesis of unprotected peptides

Area of Science:

• Organic Chemistry
• Peptide Chemistry
• Catalysis

Background:

• Peptide synthesis often requires complex protecting group strategies.
• Developing efficient methods for cyclic peptide synthesis is crucial for drug discovery.
• Olefin metathesis offers a powerful tool for C-C bond formation.

Purpose of the Study:

• To establish a protecting group-free synthesis of dicarba peptides.
• To explore the utility of ruthenium-alkylidene catalyzed olefin metathesis in peptide cyclization.
• To demonstrate the preparation of diverse cyclic peptides.

Main Methods:

• Utilizing ruthenium-alkylidene catalysts for ring-closing metathesis (RCM).
• Employing linear peptides with Z-crotyl glycine residues.
• Masking free amine groups as salts with Brønsted acids to prevent catalyst decomposition.

Main Results:

• Successful synthesis of various cyclic dicarba peptides.
• High conversion rates in RCM reactions.
• Demonstrated efficiency in both DMF and methanol solvents.

Conclusions:

• Ruthenium-catalyzed olefin metathesis provides an efficient and direct route to dicarba peptides.
• The protecting group-free strategy simplifies peptide synthesis.
• This method is applicable to a range of cyclic peptide structures.